Nano-technology, nano-electronics and nano-biology are areas of rapid growth in research and development, that are expected to lead to many important discoveries and developments of the coming years.
One of the main problems in nano-technology is how to grow or etch nanostructures in the size range of 0.1 nm to 50 nm in a fast and reliable manner on a large substrate or work piece. It is currently possible to do this on very small area of a few square micrometers using very time consuming procedures found in any standard clean room equipped with electron lithography equipment and other growth instruments. The standard method to define nano- and microstructures on surfaces has been optical lithography. Present ultraviolet optical techniques involve dimensions in the order of 100-300 nm. More recent methods include near-field optical lithography, X-ray lithography, and electron and ion beam lithography, where structures down to 20 nm may be formed. These methods require investment in expensive instruments, which may cost as much as 80 Million USD in total for a small research lab. The cost of mass production is however much higher, or as high as 3-5 Billions USD or even higher.
It is expected that new methods in nanotechnology will be able to reduce these costs. New methods such as molecular self-assembly are frequently mentioned in this regard. However, in a structure to be used in computing, the circuit layout is usually of a very irregular nature, a requirement making it very difficult to use self-assembly of molecular species as a production method.
Furthermore, nanostructures can serve many purposes other than computing, such as sensing by using physical interaction between a nanostructure and agents in liquids, solids or mixtures to determine varying properties.
Other alternatives for nanoscale processing are scanning probe microscope techniques (SPM) such as atomic force microscopy (AFM) and scanning tunneling microscopy (STM). Both techniques are used to characterize different surface properties depending on the nature of the tip-to-surface interaction. In scanning tunneling microscope (STM) the tunneling current between tip and surface probes the density of electronic states at certain energies. In atomic force microscopy (AFM), similar probing uses the forces between tip and sample to picture the surface. Both methods have been used to perform nanolithography or to transport atoms to build structures on surfaces. In these methods, individual atoms have been moved and placed on surfaces to create true nanoscopic patterns with atomic precision (0.1 nm).
These techniques share a common limitation in that they are not applicable for mass production of integrated circuits in nanoscale over a large area, where both logic components and electrical connections between them are in nanoscale. Numerous attempts have been made to create large arrays of SPM tips with individual control of the movement of the tip and sensing of either the tunneling current or the force. The complexity of such an approach is however tremendous.
There is therefore a need for a method and apparatus that allows scanning probe techniques to perform nanoscaled growth over large areas.